Ginga observations of Seyfert galaxies

We observed twenty-eight Seyfert 2 galaxies with the Japanese X-ray satellite, Ginga, and found Seyfert 2 galaxies, in general, have the X-ray spectral characteristics of obscured Seyfert 1 nuclei. This result agrees with the predictions from Unified Seyfert model proposed by Antonucci and Miller /1/. However, among the observed Seyfert 2 galaxies, there are a few galaxies with no evidence of an obscuration, contrary to the general predictions of the unified model. We note that type 2 AGN will contribute to the Cosmic Diffuse X-ray Background, if the unified Seyfert model can be extended to the far distant AGN such as quasars.     

Large angle pitch attitude maneuver of a satellite using solarradiation pressure

The force exerted by the solar radiation, though very small in magnitude, produces significant effects, especially in the case of high altitude satellites. The solar radiation pressure represents one freely available environmental force that may be put to use for various purposes. This may lead to enhancement of the life of the satellite since it consumes a very nominal amount of on-board energy. The advantages offered by the solar radiation pressure have drawn the attention of several researchers. Various controllers were proposed for many space missions, particularly for attitude control and stabilization of satellites. A controller for achieving large angle pitch attitude maneuver is described. The proposed control law is very simple in its form and requires a minimum number of on-board computations. Varieties of cases are tried and the effect of various parameters is studied     

Controlled solar sail transfers into the near-sun orbits

We present results of numerical simulations of trajectories of a space probe with a flat solar sail which moves from a circular Earth orbit to near-Sun regions. We consider the upper limit of the sail temperature as the basic restriction. We also examine the planar (ecliptic) solar sail transfer with gravity-assist flybys around planets.     

The SOHO CELIAS/SEM EUV database from SC23 minimum to the present

The SOHO Solar EUV Monitor has been in operation since December 1995 onboard the SOHO spacecraft. This instrument is a highly stable transmission grating solar extreme ultraviolet spectrometer. It has made nearly continuous full disk solar irradiance measurements both within an 8 nm bandpass centered at 30.4 nm and throughout the 0.1 to 50 nm solar flux region since launch. The 30.4 nm flux, the 0.1 to 50 nm flux and the extracted soft X-ray (0.1 to 5 nm) flux are presented and compared with the behavior of solar proxies.     

Perestroika and glasnost in the soviet space programme A personal view

For many years the world-famous Kettering Group of amateur satellite observers have confounded many more ‘official’ organization with their accucary in tracking Soviet space launches. In this article the group's founder, Geoffrey E. Perry, MBE, presents his personal perspective on current developments in the Soviet space programme. The USSR's increased openness about non-sensitive issues is to be welcomed, he concludes, but the Kettering Group has work to do yet.     

An energy management system to improve electric vehicle range andperformance

An electric vehicle (EV) energy management system (EMS) developed to accurately predict and extend the usable driving range and the life of the battery pack is discussed. The EMS monitors and records battery state of charge, vehicle performance, power consumption of key components, and driver's actions. Convenient drive inputs in conjunction with memorized energy consumption profiles allow accurate prediction of driving range and selection of appropriate recharging profiles. EV range extension is accomplished by identifying inefficient use of energy, resulting in EMS modification of energy usage by offending subsystems or EMS suggestion to the driver of improved driving habits or vehicle use. Factors affecting the accuracy of range prediction and the amount of range extension are described     

Distributed flight control system using fiber distributed datainterface (FDDI)

The design of fault-tolerant distributed control systems is discussed. The application described is a generic flight control system (FCS) for a fighter aircraft. The system is designed for high redundancy and expandability to meet various requirements. The communication network is based on the fiber distributed data interface (FDDI), which provides a high level of electromagnetic interference resistance and reliability. The choice of fiber optic media also provides an extremely high bandwidth and tremendous growth capability for future communications needs. This study is not specific to FDDI or flight control systems. The methods and configurations presented should be applicable to many real-time control implementations     

Review and analysis of the register of space objects

Parties to the Registration Convention are committed to providing the United Nations with certain information about objects they launch into space. This report describes the categories of information required, outlines the inadequacies of the present Register and suggests modifications.     

High data rate applications of ACTS technology

The NASA Advanced Communications Technology Satellite (ACTS) program will conduct high-data-rate experiments that will be applicable to the emerging broadband services of the telephony market. The existing broadband integrated services digital network (BISDN) services and delivery method as defined by the International Consultative Committee for Telephone and Telegraph (CCITT) and satellites' role in provisioning those services are discussed. The ACTS experimental efforts are summarized